Using data from the Forensic Science Service Drugs Intelligence Unit, Monkey offers you the following guide to current (January to March 1999) purity levels. Based on police seizures. Remember, there will always be variations in drug purity. Don’t assume, for example, that every bag of heroin will come out at 38.8% diamorphine - It could be more. This is just a general indication based on police seizures. Don’t treat it as gospel and end up overdosing!

Amphetamine 4%
Cocaine 62%
Crack 82.1%
Heroin 38.8%

[ you wonder sometimes why anybody bothers with your average whizz ]